Installation manual

156
6.1.10
6.1.10 Device information for combination tank PWD 750
Fig. 6.2: PWD 750 combination tank with domestic hot water preparation acc. to the flow principle
6.1.11 Country-specific requirements
Germany: German Technical and Scientific
Association for Gas and Water (DVGW) worksheet
W 551
The DVGW worksheet W 551 describes measures for reducing
the growth of legionella bacteria in domestic water systems. A
distinction is made between small systems (detached and semi-
detached houses) and large systems (all other systems with
cylinder volumes larger than 400 litres and pipe volumes larger
than 3 l between the cylinders and the extraction points).
It is recommended that the temperature controller for domestic
hot water preparation is set to 60 °C for small systems.
Operating temperatures under 50 °C should always be avoided.
The water at the hot water outlet, for example, must be heated to
a minimum of 60 °C for large systems.











1 Finned tube heat exchanger
2 Flow for domestic hot water preparation
3 Return flow for domestic hot water preparation
4 Heating water outlet
5 Heating water inlet
6 immersion heater for hot water buffer
7 Immersion heater for heating buffer
8 Flange connection for optimal
RWT 750 solar heat exchanger
9 Temperature sensor for hot water (R3)
Buffer tank temperature
1
1. Initial temperature above the circular plate
Pouring output during shower
operation
2
2. The volume of hot water refers to a mean hot water temperature of 40°C with
a flow of 15l/min, cold water inlet temperature of 10°C. As opposed to bath tub
operation, during shower operation the outlet temperature does not fall below
40 °C at the hot water extraction point.
53°C 280l
48 °C 190l
Pipe lengths with a 3 l volume
Copper pipe ∅ x mm Pipe length / m
10 x 1.0 60.0
12 x 1.0 38.0
15 x 1.0 22.5
18 x 1.0 14.9
22 x 1.0 9.5
28 x 1.0 5.7
28 x 1.5 6.1